Antenna auxiliary control circuit for directional beam scanning systems



Aug. 15,1950 c. N. NEBEL 2,518,564

ANTENNA AUXILIARY CONTROL CIRCUIT FOR DIRECTIONAL BEAM SCANNING SYSTEMS Eiled July 25, 1945 3 Sheets-Sheet 1 A TTORNEY Aug. 15, 1950 c. N. NEBEL ANTENNA AUXILIARY CONTROL cmcurr FOR DIRECTIONAL BEAM SCANNING SYSTEMS 3 Sheets-Sheet 3 Filed July 25, 1945.

ANTENNA DRIVE CAM LEFT SCAN FEED FIGS/I BLANKEO ELAN/(ED BLANKED 2 JAD'TOOTH OUTPUT TIME MODULATEDX SWEEP VOLTAGE INVENTOR CN NEBEL BY A TTORNEY Patented Aug. 15, 1950 ANTENNA AUXILIARY CONTROL CIRCUIT FOR. DIRECTIONAL BEAM SCANNING SYSTEMS Charles N. Nebel, Denville, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 25, 1945, Serial No. 607,054

Claims.

This relates in general to electromagnetic control systems and in particular to an electrical circuit for synchronizing certain auxiliary operations with the sweep of a scanning antenna.

In conventional radio ranging and detecting systems, the antenna scanning beam may be adjusted to move through a broad sector during the searching period and through one or another narrow sectors for detailed scanning after the target has been located and comes within short range. Whenever the antenna scanning sector is changed from narrow to broad or viceversa, e. g., a corresponding change must take place in the indication on the screen of the cathode-ray indicator tube.

To produce a single broad searching sector it has been proposed that a plurality of narrow antenna scanning sectors be effectively combined, as for example, a. sector lying generally to the left of the broadside or central scanning direction and another sector lying generally to the right thereof. Certain problems arise in this connection. If the antenna is of the phase velocity variation type, the direction of the antenna feed must be shifted from one end of the antenna wave guide to the other in moving the beam from either narrow sector to the other. Moreover, the indication on the cathode-ray screen must be shifted alternately between right and left sectors to correspond with the changing position of the antenna beam. And finally, since there is a slight overlap of a few milliseconds duration between the right and left antenna scanning sectors, it is necessary for the image on the cathode-ray indicating screen to be suppressed during the overlap period.

Heretofore, mechanical means have been employed to synchronize the above-described operations with the sweep of the antenna beam.

However, such mechanical devices were not found entirely satisfactory because of the speed at which operations occur and because they were inaccessible for adjustment by the operator in aircraft installations.

According to the present invention, an electrical circuit operates to synchronize operation of auxiliary circuits with the antenna sweep of a scanning antenna. The circuit in one specific form comprises a circuit breaking device which is attached to the antenna drive shaft and which actuates relays to shift the antenna feed, suppress the indication on the screen of the cathoderay tube, and reverse the sweep voltage on the indicator during designated intervals of the antenna cycle.

The primary object of this invention is to provide a more efllcient means for synchronizing the operation of auxiliary circuits with the sweep of the antenna beam in certain types of radio systems.

The nature of the present invention and its variousobjects and features may be seen from a study of the following specification and the appended drawings:

Fig. 1A shows a control circuit for reversing the antenna feed, reversing the indicator sweep voltage, and suppressing the image on the cathode-ray indicator in synchronism with the antenna scan. This circuit, which includes a magnetically operated relay of the type disclosed in the copending application of A. K. Schenck, Serial No. 607,055, filed of even date herewith, is well adapted for airplane installation;

Fig, 1B shows an enlarged and detailed view of the Schenck relay of Fig. 1A;

Fig. 2 shows an alternative circuit according to the present invention which utilizes a conventional type of circuit breaker to perform the above-named auxiliary antenna functions.

Fig. 3 shows an improved form of the circuit of Fig. 2, in which the conventional circuit breaker has been replaced with one of the type disclosed in the copending application of A. K. Schenck;

Fig. 4A shows a graphical representation of a broad antenna scanning sector comprising overlapping right-hand and left-hand scanning secors;

Fig. 4B shows an enlarged diagram of the eccentric antenna drive cam 34 of Fig. 1A;

Fig. 5A shows a graphical representation of the radial indication on the cathode-ray tube when the antenna is on the ground;

Fig. 5B shows the indication on the cathoderay tube when the antenna is at altitude H;

Fig. 50 shows a plot of the voltage output of the X-sawtooth generator; and

Fig. 5D shows a plot of the :r-sweep voltage after modulation by the antenna synchronizing operator.

The radio ranging and detecting system, of which the auxiliary antenna control circuit of the present invention is a cooperating part, comprises a large number of interdependent circuits connected to a coacting antenna, whereby the surrounding environment is scanned by a beam of pulsed microwave signals.

Referring to Fig. 1A, the transceiver 5| may be assumed to comprise microwave pulse transmitting andreceiving circuits of a type similar to those shown in Fig. 13, War Training Book 48, Preliminary Reference Manual for Radio Set AN/APQ-Y, vol. 2, and broadly similar to the microwave pulse transmitting and receiving circuits disclosed in Fig. 1A of application, Serial No. 504,577 to O. E, De Lange, filed October 1, 1943, which is now Patent No. 2,426,182, issued August 26, 1947.

Circuits of the transceiver are interconnected with the cathode-ray oscilloscope 52 through its cathode 38 and through the oscilloscope control circuits, which comprise the :1:- sweep circuit 39 connected to the a: magnetic defiecting coils 42a and 42b, and the y sweep unit 40 connected to the y magnetic deflecting coils Ma and 4"), which are biased with a positive voltage by means of the 600' volt battery 48. The

' cathode-ray oscilloscope 52 is a conventional type comprising a fluorescent screen 31 upon which the movements of the magnetically controlled beam of electrons emanating from the cathode 38 trace a visible image. The blanking grid 49 in the cathode-ray tube 52 is connected to the unblanking circuit 50, which comprises any suitable means for placing a negative voltage bias on the grid 49 of a large enough value to suppress the electron beam from the cathode 38. Circuit details of the r-sweep circuits and the ysweep and range circuits are similar to those of corresponding circuits shown in Fig. 13, War Training Book 48, Preliminary Reference Manual for Radio Set AN/APQ-7, vol. 2, mentioned above.

The secondary wave-guide 53 serves as the connecting element between the transceiver 5| and the exciting wave-guide 33 of the antenna 3|, which is of the velocity variation type disclosed in application, Serial No. 496,325 of C. B. H. Feldman, filed July 27, 1943, and which comprises an arra of dipoles 32 distributed along the leading edge of the antenna wave-guide 33, and posi tioned so that their probes extend into the interior of the guide 33 which serves as the source of excitation. The antenna guide 33 comprises a hollow pipe of rectangular cross-section formed into a substantially rectangular shape with the ends thereof joined so that energy from the transceiver 5| is fed into and withdrawn from the antenna 3I at the same point. The direction of flow of energy in the wave-guide 33 is regulated by means of the radio frequency switch 98 which comprises an aluminum vane 99 attached to a core IOI which is positioned in the field of an electromagnet I02. guide 33, to which are attached the dipoles 32, is of variable vertical dimension, the movable member 35 being positioned to ride by means of the knob 36 on the eccentric cam 34. The cam 34 is rigidly fixed to the drive shaft 66, which is attached to the antenna drive 41 through the gear reduction box 46.

Also attached to the antenna drive shaft 96, is the operating cam 11 of the relay 60 which is shown and described in detail in the copending application Serial No. 607,055 of A. K. Schenck, filed on even date herewith, and the disclosure of which is to be considered incorporated in the present specification.

The magnetically actuated contacts 62a, 52b of the relay 60 are protected from inductive surge by means of a circuit in shunt to ground which includes the 290 ohm resistance 59 in series with the 0.5 microfarad condenser 58.

A current control circuit which is goll figted in The portion of the waveshunt to ground across the electromagnet winding I0 of the relay 60 comprises the 600 ohm variable resistance 9I connected to ground 90 through the number I armature and its b contact of the relay 81, when that relay is energized, and the 2000 ohm variable resistance Si in series with the 680 ohm resistance 82, when the relay 81 is de energized. The electromagnet I0 of the relay 60 is energized by means of the 300 volt power supply 19 in series with the 15,000 ohm resistance 80.

The contact 62a of the relay 60 is connected to ground 86, while the contact 62b is connected to the energizing circuit of the relay 87, which includes the source 88 connected to ground 92.

Associated with the relay 81 are its number I and 2 armatures connected respectivel to the ground 90 and the ground 92. The a contact associated with the number I armature is connected to the grid unblanking circuit 50, while the b contact associated with the number I armature of the relay 81 is connected to the circuit of the electromagnet I0.

The switch I09 is adjustable to any one of three positions, namely, contact I which connects the ground I09 to the circuit of the electromagnet I0; contact 2 which connects the ground I09 to the grid unblanking circuit 50, or contact 3 at which the switch is unoperated. For the purposes of the description hereinafter, the switch I09 will be positioned on contact 3.

The a and 11 contacts associated with the numher 2 armature of the relay 81 are connected to a tandem operated relay circuit known as the WZ type such as disclosed by O. Cesaro in United States Patent No. 1,751,263. The WZ circuit includes the relays 93 and 94, their respective energizing batteries I03 and 95, respectively associated resistances I04 and 96, and the respectively cooperating relay armatures and associated contacts.

The switch I05 is adjustable to any one of three positions, namely, R which makes contact with the ground 54, for the right-hand antenna scanning sector; L at which the switch is open-circuited for the left-hand antenna scanning sector; and F at which the switch is connected to the WZ circuit through the b contact associated with the number I armature of the relay 94, for the broad antenna scanning sector. The contact mentioned is protected from inductive surges by means of a shunt circuit comprising the 0.5 microfarad condenser and the 240 ohm resistance 84 in series to ground.

The connection from the armature of the switch I05 leads respectively to the electromagnetic winding I02 oi the radio frequency switch 99 and the energizing circuit of the relay I06 which includes the power source I 01. The number land 2 armatures of the relay I06, which is called the sine 0 relay, are connected respectively to the a: magnetizing coils 42a and 42b of the cathode-ra tube 52. The contacts :11, b2 and (12, In of the relay I05 are connected in pairs so as to reverse the polarity of the leads 55 and 5G to the a: deflecting coils 42a and 42b.

Connections between the synchronizing generator 43 and the .r-sweep circuits is made by means of the leads 61, 68, and 69. A conventional sawtooth generator in the :r-sweep circuit is connected across the rotor of the synchronizing generator 43 by means of the input leads 61 and 68, while the output of the stationary windings of the generator 43 is connected across the leads 58 and 69, which are connected into the input of a conventional amplifier included in the :r-sweep circuits.

A roller attached to the rotor of the synchronizing generator 43 is held by means of a spring against the curved edge on the wider end of a tapered toggle arm 45, which attached at a pivotal point on its small end to a fixed bar on the wave-guide 33, and at the other point on its small end to the movable member of the antenna wave-guide 33.

Before a detailed discussion is presented of the operation of the'system, three auxiliary circuit operations will be discussed which the present invention makes possible to synchronize with the operation of the antenna.

The present embodiment of the control circuit particularly designed for airplane use, enables operation of auxiliary circuits to be synchronized with the sweep of the antenna beam in a velocity variation type of antenna such as antenna 3| of Fig. 1A. The beam of the antenna 3! is caused to sweep through a designated angle, as shown in Fig. 4A, by the rotation of the eccentric antenna drive cam 34 which is shown in an enlarged view in Fig. 4B. The rotation of the cam 34 causes a periodic variation in the vertical dimension oi. the antenna wave guide 33 by the up and down motion of the guide member 35, to which is attached a knob 36 riding on the cam 34. This operation shifts the phases of the exciting energy in the successive dipoles 32, thereby causing the antenna beam to move periodically, back and forth, through one or another of two angles or sectors depending on the end from which the antenna is excited.

The antenna 3| is so designed, that a beam approximately 0.4 degrees wide pirsses through a broad forward scanning sector of approximately 60 degrees, comprising right-hand and left-hand narrow sectors which overlap for about 1.5 degrees in the center as shown in Fig. 4A. Radiation is confined mainly to the quadrant between the horizontal line in the direction of the airplane's motion and the vertical line from the antennato the ground.

When the broad scan is performed, necessitating the movement of the antenna beam back and forth across both the right-hand and left-hand sectors, one function of the antenna auxiliary control circuit is to periodically shift the source of excitation from one end of the antenna wave guide to the other. This operation is carried out by means of the radio frequency switch 98 hereinafter known as the R. F. switch which comprises a magnetically operated stainless steel vane operating periodically during the 60-degree scan to effect the reversal of the power flow in the antenna wave guide.

A second function of the auxiliary control circuit during the broad scan is to change the sector indicated on the screen 31 of the cathoderay tube 5| in accordance with the change in the position of the antenna beam from the righthand sector to the left-hand sector or vice-versa.

In order to obtain an approximate facs mile of the ground area on the indicating screen of the cathode-ray oscilloscope it is necessary for the a and y sweep circuits to trace out a curve closely identical to the interception line of the radiated antenna pattern with the ground Plane. When the antenna is on the ground the intercept on pattern takes the form of a group of V's intersecting at a point as shown in Fig. 5A. When the antenna rises above the ground, the intersections of the conical contours of the antenna beam with the ground form a family of hyperbolas, the curvature depending on the angle of the beam as shown in Fig. 5B.

Currents proportional to the motion of the antenna beam over the ground are developed in 5 electronic circuits and super-imposed according to an J: and 11 system of coordinates so that the motion of the beam from the cathode 38 on the oscilloscope screen 3! may duplicate the 'progressive travel of the transmitted antenna beam. This is achieved by a: and y sweep circuits 39 and 40, currents from which are circulated through the deflecting coils 4 la, 4th, and 42a, 42b of the cathode ray oscilloscope 52, their" component voltages adding up vectorially to produce the desiredrmotion of the beam.

Both .1: and y sweep circuits are timed by means of a pedestal pulse which is fed in from a conventional timing pulse generating circuit included in the transceiver 5|.

The pedestal timing pulse is fed directly into the :r-sweep generatoi- 39 from the circuit of the transceiver 5| However, the pulse is delayed in the y sweep unit so that the starting time of the y sweep will correspond to the time of travel of the transmitted pulse to the ground directly beneath the airplane and back. A positive bias is placed on the y deflecting coils Ma, 4 lb, by means of the battery 48 in order to bring the indication down to the lower portion of the oscilloscope screen 31 as shown in Figs. 5A and 5B.

The time duration of the :c-saw-tooth voltage shown graphically in Fig. 5C is governed by the length of the incoming pedestal pulse which, in turn, is governed by the maximum value reouired for the y sweep in order to have it cover the oscilloscope screen. The repetition rate of the :z-saw-tooth fluctuations is adjusted in accordance with the antenna searching range.

The :rsaw-tooth voltage is fed into the rotor winding of the antenna synchronizing generator 43. The roller 44, which is on an arm attached tothe generator rotor shaft, is held against the edge of the toggle arm 45, the roller be ng drawn along the curved surface as the wave guide moves up and down. This causes the saw-tooth output of the generator 43 to be modulated in accordance with the antenna scanning angle, since the vector sum of the voltage induced in the windings of the generator 43 by the motion of its rotor varies as the sine of the angle swept by the antenna beam.

Fig. 5D shows a pot of the antenna generator output voltage against time, the reference let- 5 ters showing the generator voltages at various points in the cycle of the cam 34 correspond to the reference letters used in Fi 4A and 4B which show the positions of the antenna beam as the cam rotates. The subscripts l and 2 designate first and second cam rotations. When the antenna beam. as shown in Fig. 4A, is at position a1, slightly to the right of center, the generator output is slightly positive, as shown in Fig. 5D.

When the antenna beam moves to the straightahead position, at In, the output of the generator 43 decreases to zero. As the scanning antenna beam moves out to an angle 30 degrees to the left of center, the generator output increases to a maximum in a negative direction at or. returning to zero at d1 when the beam returns to its central position. If the anenna beam were scanning only the left-hand sector. th s same cycle would again be repeated with the second rotation of the cam 34, the generator 43 output varying from a slightly positive output at an to a maximum negative output at ca. However, when the antenna beam scans the broad sector, the output of the generator 43 is reversed by means of the sine switch, so that the slightly positive voltage as becomes the slightly negative voltage 112 when the antenna. beam begins its scan of the right-hand sector. When the antenna beam moves out to a: maximum angular scanning position at 30 degrees to the right of center, the generator voltage increases to a maximum positive output at point 02. Thus, the angle indicated on the oscilloscope screen 31 follows the angle swept by the scanning antenna beam, the sine 0 switch functioning each time the antenna beam moves from the left-hand sector to the right-hand sector or vice-versa.

A third function of the auxiliary control circuit is to suppress the image on the cathode-ray indicator screen during the interval of overlap between the right-hand and left-hand antenna scanning sectors, as shown in Fig. 4A. Fig. 5D shows the interval of blanking with reference to the magnitude and polarity of the output of the generator 63. The indicator is thus blanked while the antenna beam moves from m to b1, from d1 to a2 and from :22 to In, etc., so that for the purposes of indication, the antenna beam appears to sweep from 30 to +30 without interruption.

Fig. 1A shows the relationship between the operation of the scanning antenna and the auxiliary antenna control circuit which funtions to reverse the R. F. switch, operate the sine 0 transfer and blank the cathode ray tube indicator screen. These operations will now be described in detail.

In Fig. 1B the relay 60, which is of the type disclosed in Patent 2,289,830 to W. B. Ellwood, July 14, 1942, comprises a pair of iron strips 62a and 621) with amalgamated tips which are hermetically sealed in a longitudinal position in the'glass envelope B3. The Ellwood relay 60 is fitted into the recessed ends of the zinc plated magnetic iron poles 64a and 6417. An electromagnet I0 which is wound on the magnetic iron core II is held by means of the spacers I2 and I3 in a position parallel to the relay 60 so that the latter lies in the path of the magneticflux. The spacer 12 comprises zinc plated magnetic iron while the spacer I3 comprises non-magnetic aluminum. The zinc plated magnetic iron legs 14 and I5 protrude through the holes in the aluminum spacer I3 to enclose the air-gap I6.

The disk I5 which comprises a non-magnetic yoke 11 and soft iron shoe I8 is rigidly fixed on the antenna cam drive shaft 66 which is rotated by means of the antenna motor 41 acting through the gear reduction box 46. When the soft iron shoe I8 rotates into position closing the gap between the legs I4 and 15, the reluctance of the magnetic circuit is sufiiciently reduced to cause the closure of the magnetically responsive contacts 62a and 62b. 1

The period of closure of the contacts 62a, 62b is controlled by regulation of the flux through the electromagnet I0, which is continuously energized from the power supply I9. A current regulating circuit includes the 2,000 ohm variable resistance 8I in series with the 680 ohm resistance 82 which acts as a variable shunt to ground across the circuit of the electromagnet III. The thermistor 65 functions to maintain constant current with changes in temperature in the circuit of the electromagnet I0.

A separate control for adjusting the precise release position of the Ellwood relay is provided by the 600-ohm variable resistance 9|. When the relay 81 is energized, the number I armature engages its b contact, thereby placing the resistance 9| in shunt to ground across the resistances 8| and 82. Operation of the Ellwood relay is not affected by this reduction in voltage, since once the relay is in operation, only a relatively small current is necessary to keep it so.

Referring to Figs. 1A, 13, 4A and 4B, operation of a preferred embodiment of the control circuit adapted to reverse the R. F. switch, reverse the cathode-ray indicator and sweep voltage, and blank the indicator screen may be analyzed as follows. such as shown in United States Patent 1,751,263 to O. Cesareo, functions to enable a series of operations to recur every two revolutions of the scan drive cam. This is necessitated by the fact that one revolution of the antenna drive cam 3Q corresponds to the sweep of the beam over the right-hand or left-hand scanning sector, as shown in Fig. 4A. while two revolutions are required for a complete traverse of the broader scanning sector.

For operation of the circuit in the broad scan, the switch I05 is positioned on the F contact. The switch I08 is unoperated on contact 3. The function of the switch I08 is to prevent operation of the control relay for system adjustment purposes by applying the ground I09 through contact I, or for manual control of blanking by applying the ground I09 through contact 2.

The antenna drive cam 34 is eccentrically shaped, as shown in Fig. 43, so that as it rotates the vertical dimension of the antenna wave guide is varied from a minimum value when point 0 is in the reference position to a maximum value when point a is in the reference position. Fig. 4A shows the positions of the antenna beam during rotation of the drive cam 34; the letters in Fig. 4A corresponding to the letters on the cam 34, their subscripts 1 and 2 indicating first or second rotation.

Assume the antenna drive cam 34 to be rotating in a clockwise direction. When point a reaches the reference position, the antenna beam is in a position approximately 0.75 degree to the right of the straight-ahead position, designated as +0.75 degree on Fig. 4A. At this time, the soft iron shoe I8 of the disk TI is so positioned with respect to the legs I4 and I5 that the contacts 62a and 62b remain closed.

During the interval in which the cam 34 rotates from point a to point D, an arc of approximately 20 degrees, the contacts 62a, 62b continue to be closed, thus holding the relay 81 in operation by applying the ground 86 to its circuit.

While the relay 81 remains operated, its number I armature has functioned to break its a contact, thereby disconnecting the ground 50 from the unblanking circuit 50, so that a bias is placed on the grid 49 of the cathode-ray indicator, suppressing the beam from the cathode 38. The indicator screen 31 is thus blanked during the interval in which the antenna beam moves from +0.75 degree to 0 degree.

The number 2 armature of the relay 8! has functioned to break its a contact and engage its b contact, releasing the R. F. switch and reversing the sine 0 transfer on the indicator tube through the following circuit operations.

The ground 92 is connected to complete the A circuit of the WZ type,

energizing circuit of the relay 94, which includes the source 90 and the resistance 98.

Thus energized, the relay 94 has attracted its number I armature to break its b contact and engage its a contact, thereby removing the ground 91 from the circuit of the R. F. switch 98. The switch 98 comprises a stainless steel vane 99 attached to a rectangular shaped magnetic core IOI, which is held in position with reference to the electromagnet I02 by means of a spiral spring. When the electromagnet I02 is energized by means of a circuit which includes the 27-volt source I00, the core IOI overcomes the torque of the spring, and aligns itself with the magnetic field, thereby actuating the vane 99 to reflect the radio frequency energy from the transceiver 5| into the right end of the antenna wave guide. When the ground 91 is removed from the circuit of the electromagnet I02, the

core IN is released to return to its normal position, reflecting energy into the left end of the antenna wave guide.

Simultaneously with the release of the R. F. switch, the ground 91 is removed from the circuit of the sine 0 relay I06 which was energized by the 2'1-volt source I01. Deenergized, the relay I06 has released its armatures I and 2 to break their a contacts and engage their b contacts, reversing the current through the coils 42a and 42b of the cathode-ray indicator tube, thereby reversing the :r-sweep, as described hereinbefore.

Through its number I armature and a contact, the relay 94 is locked in operation, so that it remains energized, even after the relay 81 becomes deenergized. As long as the relay 94 remains energized, its number 2 armature remains a straight-ahead position, which is designated as 0 degrees. At this point, the soft iron shoe 18 has moved out of position with respect to the legs 14 and 15, and the contacts 62 and 82' reopen. As described hereinbefore, the exact point of opening can be regulated by means of the rheostat 9 I.

When the contacts 62a, 62b of relay 60, Fig. 13 open, the relay 81 becomes deenergized.

The number I armature of the relay 81 is released to break its b contact and reengage its a contact, thus unblanking the cathode-ray tube indicator, as described hereinbeiore.

The number 2 armature of the relay 81 is released to disengage its b contact and reengage its a contact. This operation deenergizes the relay 93 by short-circuiting it to ground 92 through a circuit which includes the number 2 armature and its a contact of the relay 94, and

the number 2 armature and its a contact of the relay 81. The I and 2 armatures of the relay 93 are thus released .to break their a contacts, while the number 2 armature engages its b contact.

Again referring to Figs. 4A and 43, while the antenna driving cam 34 rotates from point b to point e in a clockwise direction (from approximately 20 degrees to 180 degrees), the antenna beam moves from 0 degree to degrees. While the antenna cam 84 rotates irom point e to point (I (from approximately 180 degrees to 340 degrees), the beam rotates from 30 degrees back to 0 degree. During this period, the cathode-ray indicator remains unblanked, the R. F. switch is positioned so that power in the antenna wave guide flows to the left, and the sine 0 sweep is also to the left.

When the antenna drive cam 34 has rotated approximately 340 degrees, reaching the point 41 as shown in Figs. 4A and 4B, the disk has rotated so that the Ellwood contacts 62a, 82b again close, operating the relay 81, which operates the R. F. switch, sine 0 transfer and blanking relay as follows.

The number I armature of the relay 81 operates, again breaking its a contact and engaging its b contact, so that the cathode-ray indicator screen 31 is blanked during this period.

The number 2 armature of the relay 81 operates, again breaking its a contact and engaging its b contact. It should be recalled that at this. instant in the time cycle, the armatures I and.

2 of the relay 94 are operated, engaging their a contacts, and the armatures I and 2 01 the relay 93 are released, so that the number 2 armature engages its b contact. The following operations now take place.

The ground 92 is applied to short-circuit the relay 94 through a circuit which includes the number 2 armature of the relay 81 and its b contact, and the number 2 armature of the relay 93 and its 1) contact.

The armatures I and 2 of the relay 94 thereupon release to engage their b contacts, as' shown in Fig. 2. This applies the ground 91'to the circuit of the electromagnet I02, actuating the R, F. switch 98 to feed radio frequency energy to the right. Likewise, the ground 91 completes,

the circuit of the sine 0 relay I08 which thereupon actuates its armatures I and 2 to engage their a contacts, again reversing the :r-sweep voltage on the cathode-ray indicator tube.

During the interval in which the antenna drive cam 34 is rotating from point (1 to point a (approximateb 340 degrees to 0 degree), the antenna beam moves from 0 degree to approximately 0.75 degree. During the rotation from point a to point 12 beginning the second cam cycle, the antenna beam -moves from approximately 0.75 degree back to 0 degree.

As soon as the antenna drive cam 34 reaches point b in its second cycle the contacts 62a, 62b again open up, deenergizing the relay 81.

The number I armature of the relay 81 releases to engage its a contact, unblanking the cathoderay indicator screen 31 as described hereinbefore.

The number 2 armature of the relay 81 releases to engage its a contact. This causes the relay 93 to become energized by connecting its circuit to the ground 92. The relay 93 is energized by means of the source I03 acting through the resistance I04.

While the antenna driving cam 34 completes its second rotational cycle point b through P int 0 to point d (from 20 degrees to 340 degrees) in a clockwise direction, the antenna beam moves from 0 degree to +30 degrees and from +30 degrees back to 0 degrees. During this period, the cathode-ray indicator screen 31 remains unblanked, the R. F. switch is positioned so that power in the antenna wave guide flows to the right, and the sine 0 sweep is also to the right.

when the antenna driving cam 34 again reaches point d, (approximately 340 degrees), the

indicator screen is blanked, the two revolution cycle of the cam is ready to be repeated.

A better understanding of the sequence of operations may be had from a study oi the aceomp nyins table in condunction with Fig. 4A of the drawings.

sequencer! relay operations trees ar e1 are we -20 0 ted..- Operatod..-- 0pelated-..- Operated. -1!) R l easodn..- W Riel Do. 180-340 on on on Do nan A epe ral'nfl dn Tin min (in D til-180 Releasod---- Operated D 189-840 fin (in do Do, 349- 0 Operated--- Op -t do Operated d Indicator tiliitf. 1%. Sta- Screen eased .76to0 Blanked. 235:8 wtfln (1 m -a0. Unblankod. lac-s do do 30 to 0-.." Do. 340- 0 O 1 Right-- (Phi-0.75"--- Blsnked. n an -o.15mo-- Do. 23-180 in do 0to-i-30... Unblankod. 1&3-340 n +60 to 0- Do. 340- 0 Released wt... (Pin-+0.76 Blanked.

The, alternative embodiments of auxiliary antenna 'control circuits according to the present invention which are shown in Figs. 2 and 3 or thedrawings are designed to be used in conJunctioxi'with an antenna of the phase velocity variation'type, such as the antenna SI of Fig. 1. The antennas-the antenna synchronizing generator, the transceiving circuit, the x and y sweep circuits, and the cathode-ray oscilloscope. although 7 not shown in Figs. 2 and 3, are assumed to be present in the respective systems with which these two circuits cooperate, and are assumed to be similar in character and operation to those elements shown and described with reference to Fl 1A.

The embodiment of Fig. 2 is one in which a make-and-break device attached to the antenno. drive-shaft and rotating therewith is utilized instead of the magnetically actuated Schenck relay described with reference to Fig. 1A above.

Referring to Fig. 2, the rotary contactor or cam MEI is rigidly attached to the antenna driveshait M6, the contacts lilo and III!) making contact with the cam IIII continuously during its rotation. During a short interval of the cams rotation, the contacts Ilia and Illb ride on the conducting portion IIIia oi! the cam Ill, and are thereby connected to-ground II2. During the remainder of the cam's cycle of rotation, the con-- tacts Mia and i i E!) ride on the insulating portion, 5 wt. and are therefore disconnected from ground. Operation of the blanking circuit, the

sine '0 transfer, and the R. F. switch is keyed by the rotation of the cam ill, as follows.

When the contacts Mia and HID are closed, applying the ground M2, the primary blanking relay i it isenergized by the source lidand thereby actuated to pull up its number i armature to make contact to ground M5. This operation completes the circuit of the relay M6 which is energized by the battery ill. When the relay H6 is energized, it actuates its armature to break its a contact and engage its b contact, thereby big the indicating screen on the cathoderay tube.

in by means oi. a W-Z circuit.'which operates in a manner similar to that described with reference to Fig. 1. Assume that theswitch I20 has been positioned on the F contact for tho fun sweep of the antenna beam.

Whenthe ground H2 is applied to the W--Z circuit, the Z relay is energized by current passing from the source I22 through the resistance I22, the relay windings and the 0 contact to ground through the contacts In and lb. The Z relay I2I therefore pulls down its number I and 2 armatures, breaking the 0 contact, and engaging the contacts or and a2. respectively. The Z relay I2I is locked in operation by the ground I28 which is applied through the number I armature and its contact or. The ground I2! is applied through the number 2 armature and its a: contact to complete the circuit of the relay I25, which is energized by the source I24. The relay I25 then pulls down its number I armature to break its b contact and engage its a contact, thereby reversing the polarity of the sweep voltage on the indicatortube. The number 2 armature of the relay I25 is actuated to engage its a contact, thereby operating the RF switch to transfer the antenna wave guide feed, as described above.

During this operation, the W relay I25 is shortcircuited, and thereby deenergized, since ground flowing from the source I 22 through the resistance I21, the W windings, and to the ground I25, which is connected to the circuit through the number I armature and or contact of the Z relay I2I.

When the W relay I20 becomes energized, it pulls up its number I armature, breaking its a contact and engaging its b contact.

As the cam I It makes one complete revolution, again closing the contacts II Ia-I I Ib to ground 2, the W relay I26 remains energized, current passing from the source I22 through the resistance I21 and the W windings to ground at c. Simultaneously, the Z relay I2I becomes deenergized, being short-circuited by ground applied through the number I armature and I) contact of the W relay I26, and at the contact c. When the Z relay I2I becomes deenergized, it releases its number I and 2 armatures, so that the ground 52! is removed from the circuit of the relay I25.

The number I armature of the relay I25 drops back, releasing its a contact and engaging its b contact, again reversing the sine 0 voltage. The number 2 armature oi the relay I25 breaks its a contact, thereby again reversing the R. F. switch to change the direction of the antenna feed.

As soon as the ground H2 is removed from the contacts IIIa-IIIb, the W relay I25 re leases, its number i armature dropping back to engage its a contact. This conditions the circuit for a repetition of the cycle of operations The peri of operation of the relay use, and a lust described.

In the circuit of Fig. 2, the timing of the operations can be adiusted with reference to the speed of the antenna drive shaft by mechanical manipulation of the cam. In airplane installations, however, the cam in order to be in proximity to the antenna, is often placed in a position which is highly inaccessible to the operator of the radio set. This difficulty is overcome by the circuit shown in Fig. 3 which utilizes a relay having magnetically responsive hermetically sealed contacts, such as disclosed by Ellwood in Patent 2,289,830. 'The relay contacts are actuated in response to rotation of the antenna driveshaft and the duration of their closure electrically controlled as disclosed in the copending application to A. K;Schenck.

The circuit of Fig. 3, which incorporates the Schenck circuit-breaking device, operates as follows:

The Ellwood relay I30, which is positioned in a gap of the horse-shoe shaped soft iron yoke I3 I comprises resilient magnetically responsive contacts I32a and-I32b, which are hermetically sealed in the glass tube I33 encased in the non-magnetic coating I34. The permanent magnet I35 is attached to the antenna drive-shaft I30 by means of the arm I31 which is mounted rigidly on the shaft and rotates therewith. To the permanent magnet I35, the adiustable pole-pieces I30a and IBM) are attached by means of the fillister-head iron machine screws I39a and I39b.

Rotation of the permanent magnet I35 in and out of the gap I50 causes a periodic change in the magnetic flux surrounding the yoke I3I, thereby causing a periodic closure of the magnetically responsive contacts I324; and I32b, thus energizing the relay I45 by applying the ground I52 to its circuit, which includes the energizing source II.

The interval of closure of the contacts I32a and I32b is controlled by the current in the control winding I40, which is wound about the yoke I3I in such a manner as to produce the polarity indicated.

Current is fed into the control winding I40 from the battery HI, and is regulated by means of a control circuit which functions as follows. When the relay I45 is unoperated, current from the battery I flows through the resistance I22, the number I armature and its a contact, the rheostat I46, the brush I48 and the resistance I43 and through the winding I40 to ground. When the relay I45 is operated, current from the battery I4I flows through the resistance I42, the armature I44 and its b contact, the rheostat I41 and its brush I49, the resistance I43 and the winding I40 to ground. Thus, a different current passes in the bias winding I40 when the contacts 432a and I32b are open than when they are closed.

'In order to adjust the exact positions of opening and closing of the contacts 32a and 32b with respect to the position of the antenna beam, the following initial adjustments are made in the control rheostats I 40 and I41. With the relay I45 deenergized as the magnet I35 swings into place in the gap I50, the position of closure of the contacts I320. and I32b is adjusted by means of the brush I40 on the rheostat I40. Similarly, with the relay I45 operated, as the rotating magnet I35 moves out of the gap I50, the opening position of the contacts I32a and I32b is adjusted by means of the brush I49 on the rheostat I41. Rough adiustments may be made 4 by changing the positions of the pole-pieces I380 and I381) with their respective screws I391: and I30b.

As in the circuit of Fig. 2, when the contacts I32a and I321; close, the relay I45 is operated to pull up its number 2 armature to engage its a contact, thereby blanking the screen of the oathode-ray indicator tube.

Simultaneously, closing of the contacts I3!!! and I32b keys operation of the W--Z combination to shift the sine ovoltage. and the radio frequency switch", (as described with reference to Fig. 2), thus moving the antenna beam and the cathode-ray screen indication from left to right, or vice-versa, during the full sweep. Primed numerals in Fig. 3 indicate elements; the operation of which is similar to that described with reference to Fig. 2.

An auxiliary antenna control circuit designed according to the principles of the present invention is not limited to the particular embodiments herein set forth.

What is claimed is:.

1. In a velocity variation type of antenna which comprises an array of dipoles distributed along the length of a wave-guide, a cam connected to said wave-guide and rotatable to change a dimension of said guide, a driving means connected to said cam, a source of high frequency energy, a switch having a plurality of contacts, one contact of said switch adapted to move said energy source to excite the left end of said antenna wave-guide, whereby the antenna beam is caused to scan a left-hand sector, a second contact of said switch adapted to move said energy source to excite the right end of said antenna wave-guide, whereby the antenna beam is caused to scan a right-hand sector, a third contact of said switch connected to electromagnetic means operating synchronously with said antenna driving means to alternate said energy source between the right and left ends of said antenna wave-guide, thereby causing said antenna beam to scan a broad sector, comprising a combination of right and left narrow scanning sectors.

2. A radio system which comprises in combination a velocity-variation type of antenna comprising an array of dipoles distributed along the length of a wave-guide, a cam connected to said wave-guide and rotatable to change a dimension of said guide, a driving means connected to said cam, a transceiver connected to said antenna and a cathode-ray indicating device connected to said transceiver, a source of high frequency energy, a switch having a plurality of contacts, one contact of said switch adapted to move said energy source to the left end of said antenna wave-guide, and transpose the voltage on said indicator tube, whereby said antenna beam and the corresponding indication on the cathode-ray indicator are caused to scan a left-hand sector, a second contact of said switch adapted to move said energy source to the right end of said antenna wave-guide, and transpose the voltage on said indicator tube. whereby said antenna beam and the corresponding indications on the cathode-ray indicator are caused to scan a right-hand sector, and a third contact of said switch connected to electromagnetic means operating synchronously with said antenna driving means to alternate the positions of said energy source and said indicator voltage whereby the antenna beam and the indication on the cathode-ray indicator are caused to move periodically through a broad scanning sector comprising a combination of the righthand and left-hand scanning sector.

3. A radio systemwhich comprises in combination a velocity variation type of antenna comprising an array of dipoles distributed along the wave-guide, a cam connected to said wave-guide and rotatable to change a dimension of said guide, a driving means connected to said cam, a transceiver connected to said antenna and a cathode-ray indicating device connected to said transceiver, a source of high frequency energy, a switch having a plurality of contacts, one contact of said switch adapted to move said energy source to theleft end of said antenna wave-guide, and transpose the voltage on said indicator tube, whereby said antenna beam and the corresponding indication on the cathode-ray indicator are caused to scan a left-hand sector, a second contact of said switch adapted to move said energy source to the right end of said antenna waveguide, and transpose the voltage on said indicator tube whereby said antenna beam and the corresponding indications on the cathode-ray indicator are caused to scan a right-hand sector, and a third contact of said switch connected to electromagnetic means operating synchronously with said antenna driving means to alternate the positions of said energy source and said indicator voltage whereby the antenna beam and the indication on the cathode-ray indicator are caused to move periodically through a broad scanning sector comprising a slightly overlapping combination of the right-hand and left-hand antenna scanning sectors, and electromagnetic means operating synchronously with said antenna driving means to suppress the indication on said cathode-ray indicator during the period of said overlap.

4. A system of the kind described comprising a radio antenna of the velocity-variation type in which the direction of action is dependent in part on a transverse dimension of the antenna, a radio wave transceiver for applying wave energy to said antenna and receiving therefrom such applied wave energy as may be reflected from distant objects and intercepted by said antenna, driving means for periodically varying the said transverse dimension between limits such that the direction of action sweeps through one or the other of two overlapping sectors in space accordingly as said transceiver is efiectively connected to one end or the other of said antenna, switching means adapted to effectively connect said transceiver to either end of said antenna, electric contactor means operated by and in synchronism with said driving means and operative on said switching means to change the end of the antenna to which said transceiver is connected at such times that during each period of said driving means the said direction of action sweeps completely across both of said sectors in succession with a reversal within the overlapping portion of the said sectors, a cathoderay oscilloscope comprising a luminescent screen, cathode-ray deflecting means, a sweep voltage wave generator synchronized with the said driving means and adapted to deflect the cathoderayacross one or the other of two overlapping sectors on said screen according to the polarity of said sweep voltage wave, a reversing switch for reversing the polarity of said sweep voltage wave at a point in each cycle lying within the overlap portion thereof, whereby the cathode-ray sweeps across the said sectors on said screen as the said direction of action sweeps across said firstmentioned sectors, said reversing switch being actuated in response to operation of said electric contactor means, and means controlled by said contactor means for blanking said ray periodically to prevent the production of overlapping traces thereby.

5. A system in accordance with claim 4 in which said contactor means comprises an electromagnetic relay actuated once and released once at difierent points during each period of said drivingmeans dependent on an electrical bias applied thereto, means for changing the said bias from one operating value to a. second operating value during each said period, and means for separately adjusting the two said bias values.

CHARLES N NEBEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,412,703 Wolff Dec. 17, 1946 2,419,205 Feldman Apr. 2-2, 1947 2,421,747 Englehardt June 10, 1947 2,438,576 Rost et a1 Mar. 30, 1948 2,438,735 Alexanderson Mar. 30, 1948 

